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1.
A new synthesis of the pyranoquinolone alkaloids flindersine (), 8-methoxyflindersine (), N-methylflindersine (), zanthobunglanine () oricine () and veprisine () and the prenylquinolone alkaloids atanine (), preskimmianine () N-methylatanine (), O-methylglycosolone () and N-methylpreskimmianine () is described. 相似文献
2.
S.C. Pakrashi B. Achari E. Ali P.P. Ghosh Dastidar R.R. Sinha 《Tetrahedron letters》1980,21(27):2667-2670
Alangimarine (), alamarine () and alangimaridine (), isolated from the seeds of the title plant, have been characterised as a new class of alkaloids. Presence of isoalamarine () in the stem-bark is indicated. 相似文献
3.
Emir Valencia Inge Weiss Sadiqa Firdous Alan J. Freyer Maurice Shamma Alejandro Urzús Victor Fajardo 《Tetrahedron》1984,40(20):3957-3962
Three Chilean barberries, Mart. ex Schult., . Hook and [ulbar|B. Phil. (Berberidaceae), have yielded several new isoindolobenzazepine and protoberberine alkaloids. Novel isoindolobenzazepines are (±)-13-deoxychilenine (), pictonamine (), chileninone (), (±)-chileniimi () and (±)-palmanine (). Highly oxidized protoberberines of particular interest include (±)-O-methylprechilenine () and (±)-prepseudopalmanine (), together with 13-methoxy-8-oxyberberine (). Isoindolobenzazepine alkaloids arise biogenetically from the rearrangement of highly oxidized protoberberines. 相似文献
4.
Three quettamine type alkaloids, which incorporate either a benzofuran or a dihydrobenzofuran moiety within the molecular framework, have been obtained from . These are dihydrosecoquettamine (), secoquettamine (), and quettamine chloride (). Alkaloids and are racemates. Hofmann degradation of quettamine () provides secoquettamine () and the styrene which has a trans relationship between the hydrogens at C-1 and C-α, thus indicating the identical stereochemistry in quettamine. Emde reduction of quettamine leads to dihydrosecoquettamine () and the stilbene . Two other polar alkaloids in the plant are (+)-armepavine methochloride () and oblongine chloride (). An oblongine type alkaloid must be the biogenetic precursor for the quettamines. Arguments are presented favoring direct oxidative coupling in the biogenesis of the cularine alkaloids. 相似文献
5.
Herbert L. Holland David B. MacLean Russell G.A. Rodrigo Richard F.H. Manske 《Tetrahedron letters》1975,16(49):4323-4326
The reduction product of dehydrocordrastine, , with di-isobutylaluminum hydride spontaneously rearranged to the spirobenzylisoquinolines and , analogous to the alkaloids sibiricine (), corydaine (), and yenhusomidine (). 相似文献
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7.
(+)-Parviflorine (), found in Lam. (Fumariaceae), is the first known glycosidic spirobenzylisoquinoline alkaloid. Its acid hydrolysis yields (+)-parfumine () and D-glucose. Klyne's rule indicates that is a β-D-glucoside. The absolute configuration shown in expressions is predominant among spirobenzylisoquinolines. A generalization has been drawn between plant source and the oxygenation pattern of ring C for the spirobenzylisoquinoline alkaloids. 相似文献
8.
A sequence of formylation followed by a carbene insertion reaction has led to the stepwise introduction of additional ethano bridges into 4,5,7,8- tetramethyl [22](1,4)cyclophane (), providing syntheses of 5,7,8-trimethyl- [23](l,2,4)cyclophane (), a mixture of 5,8-dimethyl[24(1,2,4,5)cyclophane () and 5,7-dimethyl[24(1,2,3,5)cyclophane (, and-4-methyl[25](1,2,3,4,5)-cyclophane (). This route to completes a formal eight-step synthesis of [26](1,2,3,4,5,6)cyclophane (, superphane) with an overall yield of 17%. A Birch reduction of readily gave 12,15-dihydro-5,7,8-trimethyl[23](1,2,4)-cyclophane () in 85% yield. 相似文献
9.
Andrew T. McPhail Motoharu Ju-ichi Yukari Fujitani Mami Inoue Tian-Shung Wu Hiroshi Furukawa 《Tetrahedron letters》1985,26(27):3271-3272
The first isolation of homoacridone alkaloids, citropone-A () and -B (), from the root bark of Osbeck f. Hayata and . Hayata is described. 相似文献
10.
A new and convenient synthesis of 2-isopropylfuro-(2,3-b)quinolines () from 3-(3-methylbut-1-enyl)-2-quinolones () is described. A neat synthesis of the alkaloids (±)-lunacrine (), (±)-lunasine () and (±)-demethoxylunacrine () is also reported. 相似文献
11.
John A. Edgar Nigel J. Eggers Alan J. Jones Graeme B. Russell 《Tetrahedron letters》1980,21(27):2657-2660
A series of 14-membered ring macrocyclic pyrrolizidine alkaloids have been isolated from and . 相似文献
12.
Keiichiro Fukumoto Masatoshi Chihiro Yuichi Shiratori Masataka Ihara Tetsuji Kametani Toshio Honda 《Tetrahedron letters》1982,23(29):2973-2976
Thermolysis of a benzocyclobutene derivative () prepared from norcamphor produced stereoselectively a tetracyclic compound (), which was converted to a lactone () having correct stereochemistry at C7, C8, C9, C11, C13, and C14 positions of (±)-klaineanone. 相似文献
13.
Intramolecular reductive coupling of the bis-aldehyde(14) in the presence of Ti(0), followed by 1,4-reduction of the resulting tetraene(16) using sodium in ammonia, provides a facile synthesis of ,-verticillene(2), the putative biogenetic precursor of the taxane family of alkaloids e.g. (3). 相似文献
14.
Several atomic metastable species including N(2D), N(2D), N(2P), O(1D2), Ne(3P2), Ar(3P2), Kr(3P2 and Xe(3P2) have been detected by gas phase electron paramagnetic resonance (EPR) in a discharge-flow system. Spectra and absolute concentration are presented. 相似文献
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16.
The stereoselective synthesis of 3-O-methyl-7α--toluenesulphonyl-8α, 9α, 14β-estradiol () and its 11-oxo derivative () thermolysis of 1β--butoxy-2α-[2-(4-methoxybenzocyclobutenyl)ethyl]-2β-methy1-3α-[2-(-toluenesulphonyl)ethenyl] cyclopentane () and its oxo derivative (), which were derived from condensation product () of optically active aldehyde () and 1-cyano-4-methoxybenzocyclobutene through and to selenides and , is described. 相似文献
17.
Methods were developed to prepare 1 -methyl-, 3-methyl- and 4-0-methyl-ψ-isocytidine by selective methylation.35O-Tetraisopropyldisiloxanyl-ψ isocytidine (8) was trimethylsilylated and then treated with MeI and, after deprotection, 1 -methyl-ψ isocytidine (6) was obtained. The 2deoxy analog (7) was also prepared in a similar manner from the 2deoxy analog (10) of 8. Treatment of 8 with CH2N2 afforded the 3-methyl-ψ-isocytidine derivative (19) as the major product. Methylation with diazomethane also occurred mainly on N3 of the 2deoxy analog 10 to form 20. Removal of the 3 5O-protecting group from 19 and 20 afforded 3-methyl-ψ-isocytidine (14) and its 2-deoxy analog (15), respectively. 2-N-Acetyl- 35O-tetraisopropyldisiloxanyl-ψ-isocytidine (24), on the other hand, gave the 4-O-methyl derivative (25) as the major product upon CH2N2 treatment. Subsequent deprotection of 25 afforded 4-O-methyl-ψ-isocytidine (29). aiv51b1p33b 相似文献
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19.
Starting from 4, 5, 12, 13-tetrakis(methoxycarbonyl)[2.2]paracyclophane (), the penta-(), hexa-(–), hepta-(), and octamethyl-() derivatives have been prepared by a repetitive formylation-reduction sequence. 相似文献
20.
A total synthesis of the novel steroids DL-14α-methylestradiol () and DL-14α-methyl-19-nortestosterone () via cationic cyclization is described. Advantage was taken of the unusual stereoselectivity of Mo(CO)6/-BuOOH epoxidations. 相似文献